S1 Cold starts ok, hot starts not!

[Gatts]

S1 with cold starting problems - an auto electrician has gone through the wiring diagram, and found loads of hash jobs carried out on my car to bypass replacing faulty items. One of the problems was to do with the cold start resistor being bypassed, causing stalling and un-even running until the engine had warmed up. The solution was to replace the cold start resistor, seal some holes in the pipe between the air filter and carb, and put on a new starter motor (as the feed back to the the ignition system was on the low side (9v instead of 11.5/12v). This has cured my cold start problems, and the car idles nicely. My problem is now that the car won't start when hot, I have to either bump start it or wait for it to cool down. I am sure it's something to do with the ignition system.

Anyone had similar problems - with cure!!!?

Thanks

Gatts

[gatts]

The engine cranks and fires when cold, however when hot it cranks once (as though the battery was dead). It's not a case of plenty of crank and no spark, it just doesn't want to crank at all when hot.

The battery dial shows 11+ volts.

If I leave it an hour, it starts first time.

I read that some parts were prone to heat problems but I can't remember if the coil was the problem or the ignition unit (which are supposed to be bullet proof).

It's like the signal to the starter motor isn't getting through when hot.

The auto electrician (over the phone) suggested that I make a bypass cable from the battery to the starter connector to see if it cranks next time I try it. This should prove if its the starter or not.

I doubt it's the starter motor as I changed it for a spare on Sunday, and the problem is still there.

Very peculiar?

Any thoughts?

[Gatts]

I have cleaned and re-attached the battery earth, and am going through the process of replacing the wiring loom connectors. I have already done the main starter connection block and it still doesn't like hot starts...?

[Gatts]

Thanks Gadgit,

I'll try and get hold of a spare solenoid, and swap the cables over from the "hot" one to the "cold" one and see if that cures it. I'm not sure how to sheild it though if that is the problem - any suggestions in the bible (I'll have to buy a bible me thinks!).

Thanks again.

>> Edited by Gatts on Wednesday 11th September 12:28

[Gatts]

Update.....

Tried a different starter - problem still persists.

Cleaned all the earths and connectors - no luck!

Discussed with some friends, who suggest that my battery (a Halfords std one and not the 60a/hr specified one) may not have the power to turn the engine over when the compression in the engine is greater (i.e. when the oil has created a good seal round the cylinders/pistons/valves). And possibly, the battery is suffering from being cooked in the engine bay?

I am getting the correct battery to test this theory, and also will try taking out a couple of plugs to reduce the pressure and see if the engine cranks over.

Strangely, I ran the car with the bonnett up until it got nice and hot, turned the engine off, tried the ignition and it cranked and fired okay!

This leads me to think that it is the battery condition and possibly the wiring loom condition rather than the starter/solenoid or engine pressures.

Is there any danger of putting a bigger (higher capacity) battery on the car than the 60a/hr one specified? i.e. will it kill my alternator or overload any of the wiring? Otherwise I'll get the biggest one I can fit!

Any comments? - please!!

[Gatts]

Cheers Matt,

I'm off down the Scrap yard on Saturday to see what I can find!!

I'll let you know if it works - fingers crossed!!
Paul.

[gatts]

I will get a new one, but after I have proved if it is the battery letting me down.

I'll take a meter with me.

If it solves the problem, I'll get a nice shiney new one. If not, I'll do further investigation on the wiring loom condition from the terminal connector to the starter, and the battery to the starter, and the engine earth to the chasis.

I have already cleaned all the connectors on the starter, and the cable ends.

I'll let you know how it goes.

Cheers

Paul.

[Gatts]

Result!!

It appears that my undersize battery is not good when it gets hot under the bonnett, and my alternator is not as good as it could be (struggling to put out 12+ volts when lights/fan are on etc.)

The solution - new bigger battery, and a new alternator (poss a bigger one than the 45a one that comes as standard in an S1).

Thanks for all your suggestions,

Paul.